New York -LRB- CNN -RRB- -- Sunday 's graduation ceremony at Hofstra University was a bittersweet affair marked by a moment of silence for a 21-year-old student killed by a police officer two days ago .

Many students at the university in East Garden City , New York , wore white ribbons on their gowns in tribute to Andrea Rebello , CNN affliate WCBS reported .

`` I want to express our community 's collective grief and our sorrow over the senseless and tragic death of a very young member of the Hofstra family , '' university President Stuart Rabinowitz said . `` Our hearts and our thoughts and our prayers are with Andrea 's family , and with her friends and classmates , many of whom are in this room this afternoon . ''

She was killed by police gunfire during a confrontation between a home invasion suspect and authorities Friday night , a police spokeswoman said Saturday .

An officer fired eight shots at the intruder , who authorities say was holding a gun to Rebello 's head during a home invasion robbery at an off-campus house in Uniondale .

One shot hit Rebello in the head , Maureen Roach , a spokeswoman with the Nassau County police , said .

The intruder , whom authorities identified as Dalton Smith , 30 , of Hempstead , was struck seven times and died .

Smith invaded the home Rebello shared with her twin sister and two others during the predawn hours on Friday .

At some point , a female roommate of the twins was able to leave the home and call police , a police spokesman told CNN on Friday .

When a police officer arrived , Smith told the officer he was going to kill Rebello . He turned the handgun toward the officer , she said .

The officer , fearing for his life , drew his gun and fired , Roach said .

Authorities have not identified the officer .

At the time of the shooting , Smith was wanted for jumping parole , police said .

He was on parole for first-degree robbery and had an `` extensive '' arrest history that includes robbery , assault , and promoting prison contraband , said police in Nassau County .

A warrant for his arrest was issued April 25 for allegedly absconding from parole , police said

Rebello 's high school principal , Carol Conklin-Spillane , said the twins ' home community in Westchester was heartbroken .

She described Rebello as a fun-loving , personable and self-aware young woman .

Her parents , Fernando and Nella Rebello , are closely tied to the Portuguese community , and always worked to create opportunities for their children , Conklin-Spillane said .

Rebello , a junior , was majoring in public relations .

At Sunday 's graduation ceremony , Rabinowitz recalled a Bob Marley quote that Rebello found inspiring : `` Live the life you love and love the life you live . ''

Hofstra University said it is offering counseling to students .

A funeral Mass is planned for Wednesday .

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CNN 's Michael Martinez , Brittany Brady and AnneClaire Stapleton contributed to this report .

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Students wear white ribbons at Hofstra 's graduation

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Student Andrea Rebello was killed by police gunfire , police say

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New York home invasion suspect killed in shootout was Dalton Smith , 30

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He was on parole for first-degree robbery , Nassau County police say